This invention relates to an apparatus for removing a cladding material from the bottom portion of a control rod guide tube of a nuclear reactor.
Means for removing from a control rod guide tube (hereinafter CR guide tube) of a nuclear reactor a cladding material deposited thereon that have hitherto been proposed generally comprise an underwater pump in the form of a cleaning machine equipped with a filter for removing from the bottom portion of the CR guide tube such cladding material as has become radioactive at the time of a regular inspection, to facilitate the flow of a coolant through a reactor core. Difficulties have been experienced, however, in satisfactorily removing the cladding material deposited on the bottom portion of the CR guide tube located in a position which is about 20 meters deep in the water from the liquid level by such means, and such means have proved to have substantially no effect in removing the cladding material adhering to the surface of the bottom portion of the CR guide tube. Moreover, since a large volume of water is required for performing the operation of removing the cladding material by the aforesaid means, it is time-consuming and troublesome to subject the radioactive waste that has been recovered to a suitable treatment, and a cladding material deposited on the bottom portion of the CR guide tube cannot be effectively stripped by a stream of water usually used for such purpose. Thus, the time required for performing the cleaning operation is prolonged, resulting in an increase in exposure to radiation.